Sisyphean Ball Race Robot Toils Gracefully, Magnetically

Aren’t ball races and marble runs fun? Wouldn’t they be so much more enjoyable if you didn’t have to climb back up the ladder each time, as it were, and reset the thing? [Johannes] wrote in to tell us about a wee robot with the Sisyphean task of setting a ball bearing on a simple but fun course, collecting it from the end, and airlifting it back to the start of the track.

[Johannes] built this ‘bot to test small-scale resin printing strength as well as the longevity of some tiny linear actuators from Ali that may or may not be available at a moment’s notice. The point was to see how these little guys fared when connected directly to an Arduino or other microcontroller, rather than going the safer route with a motor driver of some kind.

Some things worked well, like the c-clips that keep the axles together, and using quick pulses to release the magnetically-linked ball from the gripper. Other aspects didn’t work out so well. Tiny resin parts do not respond well to force, for starters. And then there’s the actuators themselves. The connections are fragile and the motors are weak, but they vary wildly in quality from piece to piece, so YMMV. Some lose steps, and others occasionally seize. But you wouldn’t know any of that from the graceful movement capture in the video below. Although it appears to be automated, the bot is under remote control because of the motor issues.

Not into ball runs? There are other Sisyphean tasks available, such as moving sand around in the name of meditation.

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stages of moving a wire and enveloping an object

Attack Of The Magnetic Slime Robots

[Li Zhang] and his colleagues at the Chinese University of Hong Kong (CUHK) have developed a blob of goo that can navigate complex surroundings, grow an ‘arm’, grasp a wire and move it, encapsulate a small object and carry it. As explained in the research paper, the secret is in the non-Newtonian material the bots are made of.

You can make a similar concoction at home, usually called “slime”, with corn starch and water. Deformed slowly, it will move like a fluid. Deformed rapidly, it behaves like an elastic solid. CUHK’s version is polyvinyl alcohol, glass coated NdFeB microparticles (neodymium magnets), and borax.

This dual behavior lets the robot do amazing things.  Placed on a surface, they made the blob extend pseudopods by dragging underneath with a magnet, then used a circular field to make it grasp and transport a wire. They used a similar technique in the other axis to swallow an object. The CUHK group are promoting this as a way to retrieve foreign objects in the body (like an accidentally swallowed button cell).

Researchers will need to develop a non-toxic coating before it can be used in the body.

Nd magnets are made by sintering Nd2O3 or NdFeB in a strong magnetic field. Nd2O3 is available from SigmaAldrich at only slightly eye watering prices. Polyvinyl alcohol and borax are easily available. This seems like a hobbyist do-able project (Nd is toxic, use precautions).

We’ve been covering micro robots for some time. Back in 2014 we covered swarm micro robots. This project uses an external field to move a small Nd magnet, and all the way back in 2014 we covered early work in this field.

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Robot arm in Blender

Animate Your Robot In Blender

You’ve built a robot crammed full of servos and now you settle down for the fun part, programming your new dancing animatronic bear! The pain in your life is just beginning. Imagine that you decide the dancing bear should raise it’s arm. If you simply set a servo position, the motor will slew into place as fast as it can. What you need is an animation, and preferably with smooth acceleration.

You could work through all the math yourself. After half an hour of fiddling with the numbers, the bear is gracefully raising it’s arm like a one armed zombie. And then you realize that the bear has 34 more servos.

render of industrial robot type arm with pedestal, base, upperarm and lowerarm and IK ball

Fortunately for everybody who’s done the above, there’s Blender. It’s all about creating smooth motion for animations and computer graphics. Making robot motion with Blender is, if not easy, at least tolerable. We made a sample project, a 3-axis robot arm to illustrate. It has a non-moving pedestal, rotating base, upper arm, and lower arm. We’ll be animating it first in Blender and then translating the file over to something we can use to drive the servos with a little script.

Now, Blender is notorious for a difficult user interface. The good news is that, with revision 2.9, it moved to a much more normal interface. It still definitely is a large program, with 23 different editors and literally thousands of controls, but we’ll only be using a small subset to make our robot move. We won’t teach you Blender here, because there are thousands of great Blender tutorials online.  You want to focus on animation, and the Humane Rigging series is particularly recommended.

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Hackaday Podcast 167: Deadly Art Projects, Robot Lock Pickers, LED Horticulture, And Good Samaritan Repairs

Join Hackaday Editor-in-Chief Elliot Williams and Managing Editor Tom Nardi for a review of all the tech that’s fit to print. Things kick off with an update about the Hackaday Prize and a brief account of the 2022 Vintage Computer Festival East. Then we’ll talk about an exceptionally dangerous art project that’s been making the rounds on social media, a smart tea kettle that gave its life so that others can hack their device’s firmware, some suspiciously effective plant grow lights, and the slippery slope of remote manufacturer kill switches. We’ll wrap things up with some thought provoking discussion about personal liability as it pertains to community repair groups, and a close look at what makes synthetic oil worth spending extra on.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments below!

Direct Download link.

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A lock picking robot

This 3D Printed Robot Can Actually Pick Locks

Lockpicking is more of an art than a science: it’s probably 10% knowledge and 90% feeling. Only practice will teach you how much torque to apply to the cylinder, how to sense when you’ve pushed a pin far enough, or what it feels like when a pin springs back. Surely a robot would never be able to replicate such a delicate process, wouldn’t it?

Well, not according to [Lance] over at [Sparks and Code], who thought that building a lock picking robot would be an interesting challenge. He started out with a frame to hold a padlock and a servo motor to apply torque. A load cell measures the amount of force applied. This helps to keep the lock under a constant amount of tension as each pin is picked in succession. Although slow, this method seemed to work when moving the pick manually.

The difficult part was automating the pick movement. [Lance] built a clever system driven by two motors that would keep the pick perfectly straight while moving it horizontally and vertically. This was hard enough to get working correctly, but after adding a few additional clamps to remove wobble in the leadscrew, the robot was able to start picking. A second load cell inside the pick arm would detect the amount of force on each pin and work its way across the lock, pin by pin.

At least, that was the idea: as it turned out, simply dragging the pick across all pins in one go was enough to open the lock. A much simpler design could have achieved that, but no matter: designing a robot for all these intricate motions was a great learning experience anyway. It also gave [Lance] a good platform to start working on a more advanced robot that can pick higher-quality locks in which the dragging technique doesn’t work.

We haven’t come across lockpicking robots before; perhaps the closest equivalent would be this 3D-printed Snap Gun. If you’re interested in all aspects of locks and how to apply them, check out our Physical Security Hack Chat with Deviant Ollam.

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2022 Sci-Fi Contest: A Friendly Wall Drawing Robot

Drawing on walls is fine for children, but adults tend to get bored quickly with such antics. Even more so when they realize who is responsible for cleaning up afterwards. Instead, consider delegating those duties to a friendly helper by the name of Fumik, as [engineer2you] has done.

Fumik, who looks like a cute little jellyfish, can draw pictures up to 5 meters wide and 3 meters high, making for a massive canvas. Powered by an Arduino Mega 2560 outfitted with a CNC shield, a pair of stepper motors drive pulleys with toothed belts to move Fumik to various positions along the wall. Another smaller stepper motor is used to drive the pen forwards and backwards as needed. Fumik can be programmed to trace out various designs in SVG format. These must be converted to code and programmed into the Arduino, at which point Fumik can begin work, drawing on the wall with its pen.

It’s a fun build, and based on photos shared by [engineer2you,] Fumik is quite able at drawing clean and neat designs without a lot of smudging or jagged lines. As a bonus, it’s easy to swap out the pen, so multicolored designs can be drawn in multiple passes.

We’ve seen other robot drawing builds before, too, like this capable portrait artist. Video after the break.

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2022 Sci-Fi Contest: A Hand-Following Robot, Powered By Arduino

If there’s one thing audiences love in sci-fi, it’s a cute robot companion that follows the heroes around. If you want one of your own, starting with this build from [mircemk] could be just the ticket.

The build relies on the classic Arduino Uno microcontroller, which talks to a HC-SR04 ultrasonic sensor module and two infrared sensors in order to track a human target and follow it around. Drive is thanks to four DC gear motors, driven by a L293D motor driver, with a two-cell lithium battery providing power for everything onboard.

The robot works in a simple manner, following a hand placed in front of the robot’s sensors. First, the robot checks for the presence of an object in front using the ultrasonic sensor. If something is detected, the twin infrared sensors mounted left and right are used to guide the robot, following the hand.

It’s not a sophisticated algorithm, and it won’t really let your robot follow you down a crowded street. However, it’s a great project to learn on for beginners and could serve as a great entry into more advanced projects using face tracking or other techniques. Video after the break. Continue reading “2022 Sci-Fi Contest: A Hand-Following Robot, Powered By Arduino”